1. Field of the Invention
This invention relates in general to world globe display devices and has particular reference to a device incorporating a globe representing a planet, such as the earth, in which areas of the globe are illuminated to continually represent those areas of the planet which are currently in daylight and to also indicate the solar time at all locations on the planet.
2. Description of the Prior Art
As is well known, the earth spins about its north-south axis at the rate of one revolution per 24 hours and, at the same time, it orbits about the sun at the rate of substantially one orbit per 365 days. Since the earth's spin axis is inclined at substantially 231/2 degrees to a line perpendicular to the plane of its orbital path, it is difficult to determine or visualize at any particular time the area of the earth's surface which is currently in daylight, i.e., illuminated by the sun. The same is true for other planets. Such information, however, is of interest to students of astronomy, navigation and geography, and may also be of interest to others, such as travelers, astronauts, military planners, and persons in general.
Heretofore, earth representing globes have generally been supported by rotation about a spin axis without means for indicating, at all times, the corresponding position of that part of the earth's surface currently illuminated by the sun.